Capacitively measuring sensor and readout circuit

US5974895A · kind A · utility

Assignee

• Siemens Aktiengesellschaft · DE

Inventors

• Max Steger · Hersbruck, DE
• Thomas Scheiter · Munich, DE
• Christofer Hierold · Munich, DE
• Reinhold Noe · Paderborn, DE

Key dates

• Filing date: Jun 23, 1997
• Grant date: Nov 2, 1999
• Expiry date: Jun 23, 2017

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R27/2605
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

A capacitance to be measured is connected together with three further capacitances to form a bridge circuit, in which each two of the capacitors are connected in series, and these two series circuits are connected in parallel to one another, and which replaces a part of the input stage of a .SIGMA.-.DELTA. modulator. As inputs of this bridge circuit, terminals are provided at the ends of these series circuits, and as outputs terminals are respectively provided between the capacitors connected one after the other in series. In a sensor realized thereby, two capacitively measuring sensor elements of the same type are used. These capacitors are built into the bridge circuit together with two equally large reference capacitors in such a way that exactly one measurement capacitor and one reference capacitor is La connected is connected to each input and to each output of the bridge circuit.